Method of indirect evaporative cooling of air and device for implementation thereof

ABSTRACT

The invention relates to the field of air ventilation and conditioning by means of indirect evaporative cooling. A method for indirect evaporative air cooling comprises: forming a common air flow A before an inlet of a heat exchanger of an indirect evaporative cooling device; dividing the common air flow into two—main B and additional C—flows with the possibility of controlling their flow capacity; directing the main flow B to the heat exchanger and the additional flow C to a bypass channel; dividing the main flow B in the heat exchanger into a forward D and reverse E process flows; forming a cooled air flow F at the outlet of the air conditioner by mixing the additional C and forward process D flows at the outlet of the heat exchanger.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present patent application is a Continuation-in-part of the U.S. patent application Ser. No. 16/969,311 filed on Aug. 12, 2020 which is National stage application from the PCT application PCT/RU2018/000438 filed on Jul. 3, 2018 all of which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The group of inventions relates to the field of air ventilation and conditioning by means of indirect evaporative cooling (IEC) and can be used to create comfortable conditions and a microclimate in rooms.

BACKGROUND OF THE INVENTION

The term IEC refers to the removal of heat from a main air flow through the partition wall of a heat exchanger to an auxiliary flow that is cooled due to the evaporation of water therein. In this case, the main air flow is not moistened.

RU2031317 discloses a method for indirect evaporative air cooling and a device for performing this method. A common air flow is passed through dry channels of a first section which are in a heat-exchange state with wet channels of this section, and it is divided at the outlet into a main flow and an auxiliary flow. The auxiliary flow is directed in countercurrent to the common flow along the wetted surfaces of wet channels and is discharged into the atmosphere. The main flow is passed through dry channels of a second section which are in a heat-exchange state with its wet channels and is then supplied to a consumer. An additional flow is formed from the common flow after the first section and is directed to additional dry channels of the second section which are in a heat-exchange state with its wet channels. At the outlet of the section, the additional flow is divided and directed to the wet channels in countercurrent to the main and additional flows, whereupon the divided additional flow is discharged into the atmosphere. The flows of the wet channels at the outlet to the atmosphere are controlled according to a flow rate by a controller.

However, such a device design significantly increases the size of an air conditioner. Moreover, the use of the two successively installed wet channels complicates the adjustment of control elements, the parameters of which will depend on the current parameters of the resistance of an air duct network to which the air conditioner described in RU2031317 is connected. Specifically, when the same air conditioner is installed in different systems with different network resistances, a violation of the dependence of control levels (in %) on the position of shutters (in degrees) will be observed, and the manual introduction of a correction factor will be required.

RU2140044 discloses a method for increasing the efficiency of cooling and a device for performing this method. The method consists in dividing heat-exchange sections into sections for an auxiliary flow and sections for a main flow, installing a gas distribution chamber at the outlet from dry channels of the heat-exchange sections for the auxiliary flow, and bringing the gas distribution chamber into gas-dynamic communication with the inputs of wet channels of all the sections. This allows one to optimally distribute a cooled auxiliary flow over all wet channels with the lowest aerodynamic and heat losses, to make the ratio of the areas of cooling surfaces of the auxiliary and main flows equal to or greater than the ratio of flow rates of these flows without increasing aerodynamic resistance, as well as to increase the efficiency of heat and mass exchange in the wet channels and the cooling rate of the main flow, while significantly decreasing the aerodynamic resistance of the main flow. The division of the flows before the inlet of the heat-exchange sections allows the ratio of the flow rates to be changed by means of pressure fans, which reduces the aerodynamic resistance of the system, since there are no controllers at outlet pipes. The division of the auxiliary and main flows before the inlet of the heat-exchange sections allows air (gas) to be supplied to the heat-exchange sections for the auxiliary and main flows with different characteristics in terms of temperature and humidity. This is very important in the case of operation in a system with a dryer, when very dry air can be supplied to the heat-exchange sections for the auxiliary flow, while air with other temperature and humidity characteristics can be supplied to the heat-exchange sections for the main flow; in this case, the temperature efficiency of cooling the main flow will not depend on its humidity. By providing the device with an additional water container connected by a tube to a main container and installing an air-permeable lattice inside the outlet tube of the cooled main flow such that it is lowered into the additional water container, it is possible to collect moisture condensing in the dry channels of the main flow when the auxiliary flow with low humidity (e.g., below 5 g/kg dry air) and the main flow with high humidity (e.g., more than 10 g/kg dry air) are used. In this case, the moisture condensing from the air flow enters a main bath to moisten capillary-porous plates of the wet channels.

However, the device design known from RU2140044 does not allow one to control cooling capacity.

RU2363892 discloses a method for air conditioning with combined indirect cooling and an air conditioner for performing this method. According to the method, temperature control in a room is carried out by means of a sensor that acts on the actuator of a valve installed on a pipeline supplying a heat carrier to a heat exchanger, and humidity control is carried out according to a pulse from a sensor acting on the actuator of an air valve. The pulse allows one to change the ratio of flow rates of the air processed in a spray air washer and passed through a bypass channel, with one end of the bypass channel being connected to the cavity of the air conditioner before the spray air washer and the other being connected to the cavity of the air conditioner after the spray air washer. After that, the air is removed from the room through air distribution devices and an outlet air duct with an exhaust hood, while returning a part of the recirculated air into a mixing chamber.

However, in the method known from RU2363892, the efficiency of the indirect cooling control process is low. It should be also noted that the mixing of air flows in the spray air washer negatively affects microbiological parameters of the resulting air. When water having an inappropriate quality in terms of biological parameters is used, bacteria may enter the conditioned air.

SUMMARY OF THE INVENTION

The technical problem of the group of inventions is to develop a simple and effective method for controlling the cooling capacity of indirect evaporative air cooling, while maintaining a constant air flow rate.

The technical result consists in the possibility of controlling temperature at the outlet of a heat exchanger and, consequently, an indirect evaporative cooling device (i.e., an air conditioner).

The technical problem of the group of inventions is solved by a method for indirect evaporative air cooling. The method consists in forming a common air flow in an air intake section before an inlet of an IEC heat exchanger, forming main and additional air flows, controlling the cooling capacity of an air conditioner and the temperature of cooled air at the outlet of the indirect evaporative cooling device. According to the solution, at the inlet to the heat exchanger, the common air flow is divided into two—main and additional—flows, while providing the possibility of controlling their flow rates. The main flow is directed to the heat exchanger, and the additional flow is directed to a bypass channel. Then, the main air flow in the IEC heat exchanger is divided into direct and reverse process flows. Hydraulic resistance values of the IEC heat exchanger and the bypass channel are set to be equal. Further, the additional and direct process air flows are mixed at the outlet of the heat exchanger. A cooled air flow is formed in a mixing chamber and fed to the outlet of the indirect evaporative cooling device. The absolute flow rate values of the reverse process air flow and the cooled air flow at the outlet of the device are retained constant.

The technical problem of the group of inventions is also solved by a device for implementing the method, which comprises an air intake section, an indirect evaporative cooling heat exchanger and a process section, which are all arranged in series, as well as a bypass channel, one of the ends of which is connected to the process section. According to the solution, the device further comprises a process-flow ejection section which is rigidly connected to the heat exchanger and arranged above the heat exchanger. The process-flow ejection section is formed as part of the reverse cooled main flow. The device further comprises at least one shutter arranged in front of the heat exchanger. The bypass channel is equipped with a shutter arranged on the side of the air intake section, in which the other end of the bypass channel is connected.

BRIEF DESCRIPTION OF THE DRAWINGS

The method is explained by the drawings in which:

FIG. 1 shows a scheme for controlling cooling capacity using a bypass channel arranged on an external side of a housing;

FIG. 2 shows a scheme for controlling the cooling capacity using a bypass channel arranged inside the housing;

FIG. 3 shows a dependence of the cooling capacity on a position of shutters in a two-shutter system;

FIG. 4 shows a dependence of the cooling capacity on the position of the shutters in a one-shutter system.

LISTING OF REFERENCE NUMERALS IN THE DRAWINGS

-   1—IEC heat exchanger; -   2—bypass channel; -   3—air intake section; -   4—mixing chamber; -   5—process-flow ejection section; -   6—control shutter on the bypass channel; -   7—control shutter in front of the IEC heat exchanger 1; -   8—air treatment (noise damping, filtration, humidification, heating,     drying) sections; -   9—frame; -   10—water supply module; -   11—housing; -   A—common air flow at the inlet of an IEC device (air conditioner); -   B—main air flow entering the IEC heat exchanger 1; -   C—additional air flow passing through the bypass channel; -   D—forward air flow cooled in the IEC heat exchanger 1; -   E—reverse process flow moistened in the IEC heat exchanger 1 and     taking heat from the flow D; -   F—cooled air flow at the outlet of the air conditioner.

DETAILED DESCRIPTION OF THE INVENTION

An indirect evaporative cooling device, which performs a method for indirect evaporative air cooling, comprises: an air intake section 3; air treatment sections 8; an IEC heat exchanger 1 and a bypass channel 2, which are separated from the air intake section by shutters 7 and 6, respectively; a process flow ejection section 5 rigidly connected to the heat exchanger 1; a mixing chamber 4; an air conditioner frame 9; and a water supply module 10 for the heat exchanger 1. The bypass channel 2 may be arranged on the external side of a housing 11 (see FIG. 1) or inside the housing 11 (see FIG. 2).

The air intake section 3 is arranged between the air treatment sections 8 and the IEC heat exchanger 1. At least one control shutter 7 is arranged on the side of the air intake section 3 of the IEC heat exchanger 1. The mixing chamber 4 is arranged after the IEC heat exchanger 1 and serves to mix an air flow D passed through the IEC heat exchanger 1, with a flow C passed through the bypass channel 2. The bypass channel 2 is equipped with the shutter 6 on the side of the air intake section 3. One of the ends of the bypass channel 2 is connected to the air intake section 3, while another of the ends of the bypass channel 2 is connected to the mixing chamber 4.

In the IEC heat exchanger 1, the air flow C is divided into a forward air flow D and a reverse process air flow E, and the indirect evaporative cooling of the air flow D takes place. After cooling, the flow D is supplied to the mixing chamber 4. The air flow C is supplied to the mixing chamber 4 after passing the bypass channel 2, without changing its physical parameters.

The bypass channel 2 may be formed both from the external side of the housing (see FIG. 1) and inside the housing (see FIG. 2).

The air intake section 3 and the process chamber 4 may be implemented as both empty sections and sections with equipment (a fan, etc.). FIG. 1 and FIG. 2 show an embodiment in which the air intake section 3 is equipped with a fan, while the process section 4 is shown empty.

The method for indirect evaporative air cooling is carried out as follows. After the air treatment section 8, a common air flow A enters the air intake section 3, where it is divided into air flows B and C by means of the control shutters 6 and 7. The air flow B is supplied to the IEC heat exchanger 1, while the air flow C is supplied to the bypass channel 2.

When the system with the two shutters 6 and 7 is used as a controller, the cooling capacity (Qx) may be adjusted in the range from 0 to 100% of its maximum. When the shutter 6 is fully closed and the shutter 7 is open, the common air flow A fully goes, without division (A=B), through the IEC heat exchanger 1 (maximum cooling capacity). Conversely, when the shutter 6 is open and the shutter 7 is closed, the common air flow A fully goes, without division (A=C), through the bypass channel 2 (zero cooling capacity).

The dependence of the cooling capacity on the position of the shutters in the system with the two shutters 6 and 7 is shown in FIG. 3, where 100% shutter position means that the shutter is fully open, 0% means that the shutter is fully closed. The shutters may be made using a rotary mechanism (rotating, ball), a translational mechanism (gate), a variable aperture mechanism (iris), or any other mechanism that can change the cross-section of the air passing therethrough.

When the system with one shutter 6 installed directly at the border of the air intake section 3 and the bypass channel 2 is used as a controller, the air flow goes, in extreme positions, either fully through the IEC heat exchanger 1 (maximum cooling capacity, A=B), or, in the ratio of 50/50%, through the IEC heat exchanger 1 and the bypass channel 2 (50% cooling capacity, A=B+C, where B=C). The dependence of the cooling capacity on the position of the shutters in the system with one shutter 6 is shown in FIG. 4, where 100% shutter position means that the shutter is full open, 0% means that the shutter is fully closed.

The air flow B in the IEC heat exchanger 1 is divided into the cooled forward flow D, which is transferred to the mixing chamber 4, and the process reverse flow E, which is removed to the atmosphere through the process-flow ejection section 5.

As a result of mixing the flows C and D in the mixing chamber 4 in different proportions, the cooling capacity of a working flow F at the outlet of the air conditioner is controlled.

When the cooling capacity is controlled with the control shutter 6 on the bypass channel, the key factor in maintaining constant flow rate values of the working flow F and the process reverse flow E is the equality of hydraulic resistance values of the IEC heat exchanger 1 and the bypass channel 2 when air is supplied only through the IEC heat exchanger 1 or only through the bypass channel 2. This may be achieved both by reducing the cross-section of the bypass channel 2, and by using additional corrective hydraulic resistance with the aid of a shutter, a gate or a valve on the bypass channel 2.

With an increase in the air flow rate of the additional flow C, a proportional decrease in the air flow rate of the main flow B occurs. Due to the movement of the air along the bypass channel 2 for the forward air flow D, resistance at the inlet of the mixing chamber 4 increases—the more the shutter 6 opens, the higher the flow rate of the additional air flow C and the stronger the resistance acts on the forward flow D, thereby reducing its flow rate. When the hydraulic resistances on the IEC heat exchanger 1 and the bypass channel 2 are equal and when the opening of the bypass channel 2 occurs, a change in the proportions between the flows D and E is observed (the share of E increases, while the share of D decreases), but the absolute flow rate value of the process reverse flow E remains unchanged. Therefore, the air flow rate of the working flow F also remains unchanged. This process is observed during the whole period of opening the shutter 6 on the bypass channel.

When performing additional control such that the cooling capacity is reduced to less than 50% of its maximum, it is required to close the shutter 7 in front of the IEC heat exchanger 1. The closing of the shutter 7 leads to an increase in the resistance of the IEC heat exchanger 1, for which reason the flow rates of the flows D and E are reduced. The reverse process flow E is auxiliary and is not interesting from the point of view of room air conditioning. A reduction in the flow rate of the reverse process flow E will have no consequence for a conditioned-air consumer.

Given below are implementation examples of the claimed group of inventions.

In the examples, the hydraulic resistances of the IEC heat exchanger 1 and the bypass channel 2 are considered equal (R1=R2=R).

It is conveniently assumed that the pressure is atmospheric outside the air conditioner (at the inlet of the air conditioner and at the outlet of the flows F and E).

Let us set the following values: D=¾ B, and E=¼ B.

Example 1

The shutter 7 is fully open, while the shutter 6 is closed.

Then, the cooling capacity is equal to 100% (Qx=100%) of the maximum. The whole flow A goes through the IEC heat exchanger 1.

In this case, the common air flow A at the inlet of the air conditioner will be equal to the main air flow B entering the IEC heat exchanger 1. There is no additional air flow C passing through the bypass channel.

E=¼B(E=¼A);

D=¾B(D=¾A);

F=D(F=¾A).

Example 2

The shutter 6 is slightly open, while the shutter 7 is fully open.

When opening the shutter 6, the flows are divided. Since the resistances R1 and R2 are initially equal, the flows will be divided in the ratio of 50/50% of A on the fully open shutter 6. When the shutter 6 is opened by 10%, 10% of 50% A, i.e., 5% of A, will go into the bypass channel 2.

Thus, the main flow B in the amount of 95% of the common flow will pass through the shutter 7, and the additional air flow C in the amount of 5% of the main flow will pass through the shutter 6. That is, B=0.95 A, and C=0.05 A.

Further, according to simple mathematical logic, the following should happen:

D=¾B=>D=¾×0.95A=>D=0.7125A.

E=¼B=>E=0.2375A.

F=C+D=0.05A+0.7125A=0.7625A.

Given this logic, there is a violation of the original proportions, where the flow F=0.75 A.

However, if one considers the fact that an increase in the amount of air in a limited volume increases the pressure inside, it will be clear that the throughput of the mixing chamber 4 will decrease. The air will flow along the path of least resistance, and if one considers that there are two outlets from the air conditioner (the flows F and E), then the air will rush from the flow F to the flow E, since the resistance is less thereon.

The air will flow from the flow F to the flow E until an equilibrium state is provided, i.e., when the resistance on the flow E becomes equal to the resistance on flow F. This means that the following relationships will again be correct: F=¾ A and E=¼ A.

The same will be observed with any change in the air flow rate when opening the shutter 6.

When the shutter 6 is fully open, the cooling capacity drops to 50% of the maximum.

Further, it is necessary to close the shutter 7 in order to provide a further reduction in the refrigerating capacity. When it is closed, the equality of resistances R1=R2 will be violated, since the shutter 7 will create additional resistance on the IEC heat exchanger 1 and R1 will become larger than R2. Therefore, the flow rate of the air flows F and E will change: F will increase, E will drop.

Since the flow rate of the reverse process flow E is not interesting from the point of view of room air conditioning, and the flow F will exceed the initially set value for a consumer, it will be required to adjust the common air flow. This can be achieved by increasing the resistance at the outlet of the air conditioner (by installing a shutter on the flow F after the air conditioner) or reducing the fan consumption by applying a method for decreasing its speed.

Thus, the simple and effective method for controlling the cooling capacity of indirect evaporative air cooling, while maintaining a constant air flow rate, has been developed. This method allows one to control the temperature at the outlet of the heat exchanger and, consequently, the indirect evaporative cooling device (the air conditioner). 

1. A method for indirect evaporative air cooling, comprising: forming a common air flow A before an inlet of a heat exchanger 1 of an indirect evaporative cooling device; dividing the common air flow into two—main B and additional C—flows with the possibility of controlling their flow capacity; directing the main flow B to the heat exchanger 1 and the additional flow C to a bypass channel 2; dividing the main flow B in the heat exchanger 1 into a forward D and reverse E process flows; forming a cooled air flow F at the outlet of the device by mixing the additional C and forward process D flows at the outlet of the heat exchanger 1; wherein hydraulic resistance values of the heat exchanger 1 and the bypass channel 2 are set equal, wherein absolute flow rate values of the reverse process flow E and the cooled flow F at the outlet of the device are retained unchanged.
 2. An indirect evaporative cooling device for performing the method according to claim 1, comprising: an air treatment section 8, an air intake section 3, an indirect evaporative cooling heat exchanger 1, a mixing chamber 4, which are all arranged in series; a bypass channel 2 having one end connected to the air intake section 3 and another end connected to the mixing chamber 4; a reverse-process-flow ejection section 5 rigidly connected to the heat exchanger and arranged above the heat exchanger; wherein at least one shutter 7 is arranged in front of the heat exchanger 1; and wherein the bypass channel 2 is equipped, on one side of the air intake section 3, with a shutter 6 for controlling a cooling capacity of the indirect evaporative cooling device.
 3. The device according to claim 2, wherein the bypass channel 2 is arranged on an external side of a housing
 11. 4. The device according to claim 2, wherein the bypass channel 2 is arranged inside a housing
 11. 